What is ‘slugging,’ and what do skin-care experts think of this beauty hack?

It’s rare for TikTok beauty trends to hold merit with dermatologists and aestheticians — with the overwhelming exception of “slugging.”

Slugging is a catchy term that means slathering your face with petroleum jelly as the last step of your evening skin-care routine. The practice leaves your face as slimy as slug mucus (hence the name).

Supposedly initially a K-Beauty trend, the term slugging appears to have first surfaced in the United States in a 2014 post in a Reddit subgroup. But it didn’t go viral until Charlotte Palermino, a New York-based licensed aesthetician and co-founder of skin care company Dieux, introduced the concept to her TikTok and Instagram followers in September 2020, telling them it had made her dry skin “juicy.” As of press time, the hashtag #slugging has 235.5 million views on TikTok.

Petroleum jelly, which is also known as petrolatum and was first sold by Vaseline, is a white or yellowish semisolid substance made up of a mixture of complex hydrocarbons by dewaxing crude oil. According to Joshua Zeichner, a dermatologist and associate professor of dermatology at Mount Sinai Hospital in New York, it is an occlusive ingredient: “It forms a seal over the stratum corneum (outer layer of skin or skin barrier) to protect the skin from the environment while preventing water loss.”

By forming this seal — which keeps dirt and bacteria out and moisture in — the petroleum jelly creates the ideal environment to allow your skin to repair itself, Zeichner said. And, he and Palermino said, slugging doesn’t require much petroleum jelly. You can use a pea-size portion for your entire face.

Though slugging is a new name for it, the act of applying petroleum jelly as a skin protectant is nothing new. In the 15th century, members of the Native American Seneca tribe, who dug oil pits in northwestern Pennsylvania, used petroleum jelly on human and animal skin to protect wounds, stimulate healing, and keep the skin moist. In the late 19th century, American chemist Robert Chesebrough, visiting oil fields in the same area of northwestern Pennsylvania, observed oil workers applying the residue from their oil drills on their wounds. Chesebrough brought a sample back to his Brooklyn lab, purified it, tested it on his self-inflicted wounds, and in 1870 branded his “miracle jelly” as Vaseline.

Although petroleum jelly is considered non-comedogenic (meaning it won’t clog pores) because its molecular size is too large to penetrate deep into the skin, Massachusetts dermatologist Ranella Hirsch warned that slugging is not for everyone. “Generally speaking, I don’t tend to recommend it for people who are prone to milia, oily or acne. I just find occlusives aren’t a good marriage for them.” Hirsch recommends patch-testing first for these skin conditions and whether you are prone to allergic reactions.

For severely dry skin, Susan Taylor, a Philadelphia-based dermatologist and founder of the Skin of Color Society, warns that petroleum jelly, alone, will not moisturize the skin. “I have my patients put the petroleum jelly over a moisturizer that has humectant and emollient ingredients.” Taylor also tells patients to apply petroleum jelly when skin is damp to “trap in the moisture.”